THE MAMMARY GLAND. 443 



rest, will materially affect the size and shape of the capillary 

 networks. They are, however, much less distinct and con- 

 spicuous during the period of lactation than in the quiescent 

 state of the gland. Rauber found in the glands of pregnant 

 animals that the blood-vessels were not in immediate contact 

 with the walls of the secreting vesicles, being separated from 

 them by interposed lymph-channels. Coyne, Langhans, and 

 Kolessnikow have also described these perialveolar lymph- 

 spaces. Their presence is, indeed, readily demonstrated by 

 injections with nitrate of silver solutions. In actively secreting 

 glands these channels are sometimes packed with leucocytes, 

 which also infiltrate the stroma of the organ. 



Lymphatics are plentiful in the mammary gland. We find 

 them subcutaneously, as well as deep in the interior of the 

 organ. Coyne, in 1874, described the perialveolar lymph- 

 spaces, already mentioned, for the human mamma, and Koless- 

 nikow, in 1870, perialveolar lymph- spaces for the mammary 

 gland of the cow. Langhans succeeded in injecting a rich net- 

 work of periacinal lymph-vessels, likewise lymph-channels 

 around the excretory ducts and the lacteal sinuses. The lar- 

 gest lymph-vessels are retro-glandular. They are without 

 valves. The lymph-vessels of the nipple resemble those of 

 the skin. There seems to be no free communication between 

 the lacunal and interstitial spaces of connective tissue of the 

 glands, and the proper lymph-channels. 



The principal lymph-vessels of the mamma, both deep and 

 superficial branches, proceed to the glands of the axilla. But 

 some of the mammary lymphatics also communicate, through 

 intercostal branches, with the thoracic lymphatic glands. 

 These are points worthy of remembrance in studying the mode 

 of dissemination in mammary tumors. 



Nerves abound less in the secreting structure of the mam- 

 ma than in its integumentary apparatus. The majority are of 

 spinal origin, although the sympathetic system is by no means 

 excluded from representation. Branches from the fourth, 

 fifth, and sixth intercostal nerves the so-called rami glandu- 

 lar es accompany the milk-ducts, and ramify within the organ. 

 Satisfactory evidence concerning the manner of their ultimate 

 termination has, however, not been hitherto obtained. Most 

 of the nerves in the interior of the organ belong to the vascular 

 or vaso-motor variety, and many are seen to accompany the 



